Sputtering, alternatively called physical vapor deposition (PVD), has long been used in depositing metals and related materials in the fabrication of semiconductor integrated circuits. Its use has been extended to depositing metal layers onto the sidewalls of high aspect-ratio holes such as vias or other vertical interconnect structures. Currently, advanced sputtering applications include depositing a metallic seed layer for later electroplating of the metallic layer in the via and depositing a barrier layer on the dielectric material of the via sidewall to prevent the metallic layer from diffusing into the dielectric.
For example, titanium nitride (TiN) metallization has been used for a number of years in back end of the line (BEOL) and front end of the line (FEOL) semiconductor applications. One exemplary application is for a hard mask which is a BEOL application with multiple layers or passes per device on the substrate. The requirement is to deposit a blanket TiN layer that will act as both a patterning layer and a hard mask. TiN is a metal layer having a number of desirable qualities. However one significant down side is the inherent stress and tendency of TiN layers to crack, peel, and flake, thus generating defects.
Thus, the inventors have provided a magnet configuration that can advantageously be used to deposit materials while improving particle performance.